1. Field of the Invention
The present invention relates generally to lateral double diffused metal oxide semiconductor (LDMOS) devices. More particularly, the present invention relates to lateral double diffused metal oxide semiconductor (LDMOS) devices with enhanced performance.
2. Description of the Related Art
Semiconductor integrated circuit microelectronic fabrications are formed from semiconductor substrates within and upon which are formed semiconductor devices, and over which are formed patterned microelectronic conductor layers which are separated by microelectronic dielectric layers.
Common in the art of semiconductor integrated circuit microelectronic fabrication are logic semiconductor integrated circuit microelectronic fabrications, memory semiconductor integrated circuit microelectronic fabrications and embedded (i.e., integrated logic and memory) semiconductor integrated circuit microelectronic fabrications which operate at a generally low supply voltage of from about 2.5 to about 5.0 volts. Such semiconductor integrated circuit microelectronic fabrications are typically fabricated while employing conventional field effect transistor (FET) devices which comprise a semiconductor substrate having formed therein a pair of source/drain regions separated by a channel region, over which channel region is formed a gate electrode.
Considerably less prevalent, but nonetheless also conventional in the art of semiconductor integrated circuit microelectronic fabrication, are semiconductor integrated circuit microelectronic fabrications which operate at considerably higher operating voltages in a range of from about 5 to about 1000 volts. Such semiconductor integrated circuit microelectronic fabrications are often employed as switching elements within higher voltage or higher current electrical circuit applications. In addition, such semiconductor integrated circuit microelectronic fabrications are often fabricated while employing lateral double diffused metal oxide semiconductor (LDMOS) devices. Lateral double diffused metal oxide semiconductor (LDMOS) devices are field effect transistor (FET) devices which bear a certain resemblance to conventional field effect transistor (FET) devices insofar as they also comprise a pair of source/drain regions formed within a semiconductor substrate and separated in part by a channel region also formed within the semiconductor substrate, the channel region in turn having formed thereover a gate electrode. However, lateral double diffused metal oxide semiconductor (LDMOS) devices differ from conventional field effect transistor (FET) devices in part insofar as while a pair of source/drain regions within a field effect transistor (FET) device is typically fabricated symmetrically with respect to a gate electrode within the field effect transistor (FET) device, within a lateral double diffused metal oxide semiconductor (LDMOS) device a drain region is formed further separated from a gate electrode than a source region, and the drain region is additionally formed within a doped well (of equivalent polarity with the drain region) which separates the drain region from the channel region.
While lateral double diffused metal oxide semiconductor (LDMOS) devices are thus clearly desirable within the art of semiconductor integrated circuit microelectronic fabrication, lateral double diffused metal oxide semiconductor (LDMOS) devices are nonetheless not entirely without problems in the art of semiconductor integrated circuit microelectronic fabrication. In that regard, it is often difficult within the art of semiconductor integrated circuit microelectronic fabrication to efficiently fabricate lateral double diffused metal oxide semiconductor (LDMOS) devices with enhanced performance.
It is thus desirable in the art of semiconductor integrated circuit microelectronic fabrication to provide lateral double diffused metal oxide semiconductor (LDMOS) devices which may be efficiently fabricated with enhanced performance.
It is towards the foregoing object that the present invention is directed.
Various lateral double diffused metal oxide semiconductor (LDMOS) devices having desirable properties, and methods for fabrication thereof, have been disclosed in the art of semiconductor integrated circuit microelectronic fabrication.
Included among the lateral double diffused metal oxide semiconductor (LDMOS) devices and methods for fabrication thereof, but not limiting among the lateral double diffused metal oxide semiconductor (LDMOS) devices and methods for fabrication thereof, are lateral double diffused metal oxide semiconductor (LDMOS) devices and methods for fabrication thereof disclosed within: (1) Eklund, in U.S. Pat. No. 5,146,298 (a semiconductor device which may function as either a lateral double diffused metal oxide semiconductor (LDMOS) device or a bipolar transistor device, by fabricating the semiconductor device with an extended drain region); and (2) Ludikhuize, in U.S. Pat. No. 6,288,424 (a lateral double diffused metal oxide semiconductor (LDMOS) device with attenuated charge carrier to substrate charge injection, through use of a buried screening layer fabricated within the lateral double diffused metal oxide semiconductor (LDMOS) device).
Desirable in the art of semiconductor integrated circuit microelectronic fabrication are additional lateral double diffused metal oxide semiconductor (LDMOS) devices which may be efficiently fabricated with enhanced performance.
It is towards the foregoing object that the present invention is directed.
A first object of the present invention is to provide a lateral double diffused metal oxide semiconductor (LDMOS) device.
A second object of the present invention is to provide the lateral double diffused metal oxide semiconductor (LDMOS) device in accord with the first object of the present invention, wherein the lateral double diffused metal oxide semiconductor (LDMOS) device is efficiently fabricated with enhanced performance.
In accord with the present invention, there is provided by the present invention a lateral double diffused metal oxide semiconductor (LDMOS) device and a method for fabricating the lateral double diffused metal oxide semiconductor (LDMOS) device.
The lateral double diffused metal oxide semiconductor (LDMOS) device comprises in a first instance a semiconductor substrate of a first polarity having formed thereupon an epitaxial layer of a second polarity opposite the first polarity. The lateral double diffused metal oxide semiconductor (LDMOS) device also comprises a source region of the first polarity separated from a well region of the first polarity by a channel region of the second polarity, the well region having formed therein and further separated from the channel region a drain region of the first polarity, where the source region, the channel region, the well region and the drain region are formed laterally sequentially adjoining within the epitaxial layer. The lateral double diffused metal oxide semiconductor (LDMOS) device also comprises a gate electrode formed over the channel region. Finally, the lateral double diffused metal oxide semiconductor (LDMOS) device comprises a buried layer isolation region of the first polarity formed aligned beneath the well region and separated therefrom by a portion of the epitaxial layer.
The lateral double diffused metal oxide semiconductor (LDMOS) device in accord with the present invention contemplates a method for fabricating the lateral double diffused metal oxide semiconductor (LDMOS) device in accord with the present invention.
The present invention provides a lateral double diffused metal oxide semiconductor (LDMOS) device, wherein the lateral double diffused metal oxide semiconductor (LDMOS) device may be efficiently fabricated with enhanced performance.
The present invention realizes the foregoing object by forming within a lateral double diffused metal oxide semiconductor (LDMOS) device a buried layer isolation region of a first polarity formed aligned beneath a well region of the first polarity (in turn having formed therein a drain region of the first polarity) and separated therefrom by a portion of an epitaxial layer of a second polarity opposite the first polarity.